Unless the terminology is very different from the programs I've used,
Diffuse = direct lighting from the sun
Ambient = fill light made by reflected surroundings or atmosphere
Emissive = a glow, or self-emitting light source (like fire), not dependent on exterior lighting
Specular = Glossiness, or strength of highlights
Power = would be the strength of all of those together for the combined effect.
Using Kweassa's posted Ki-84 settings as an example, the skin would be: 26% lit by surrounding light, 66% lit by direct light, 0% glow, and 40% glossy. The combination of all these settings has been applied with 33.42% strength.
An ambient setting of 0, 0, 0 would give you black black bible-black shadows. 1, 1, 1 would give you no shadows at all.
Specular of 0, 0, 0 would create a soft (or nonexistent) highlight, like on matte paint. Specular of 1, 1, 1 would make an extreme hotspot of a highlight, like on chrome.
You would not use Emissive on an aircraft, only on objects like fires or lights.
My guess would be that the only setting that we would really ever play with for aircraft skins would be the Specularity setting, and maybe the Power.
For an example of the RGB values, let's say you wanted to give a metal aircraft more of a bluish reflection, you would use numbers like 0.25, 0.25, 0.38 (R, G, and B... Blue being the stronger value) but I seriously don't think this is something you want to mess around with.
Looks like we're in for a lot of experimenting, eh?
